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mattermost
34.5k
Other
Mattermost is an open source platform for secure collaboration across the entire software development lifecycle..
Updated: 2025-12-05
Privacy First
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Rocket.Chat
44.0k
Other
The communications platform that puts data protection first.
Updated: 2025-12-05
zulip
23.9k
Apache License 2.0
Zulip server and web application. Open-source team chat that helps teams stay productive and focused.
Updated: 2025-12-05
chat
13.0k
GNU General Public License v3.0
Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots
Updated: 2025-11-29